Offshore wind farms as “heat pumps”?

What the new ocean-warming study really shows

A new paper in Science Advances has given critics of offshore wind plenty of ammunition: under certain conditions, large offshore wind clusters do in fact warm the sea surface by about 0.3–0.4°C along the US East Coast.(PubMed)

That sits very awkwardly next to the political marketing of offshore wind as a climate-neutral, almost consequence-free technology. But does it justify talking about a “climate hoax” – or are we looking at a real effect that’s being oversold for political effect?

Let’s unpack what the science actually says.

What did Seo et al. really find?

The study by Hyodae Seo and colleagues uses a fully coupled ocean–atmosphere–wave model to simulate huge offshore wind farm clusters in seasonally stratified shelf seas. The test area: the US East Coast, but the physics applies very directly to North Sea–style build-outs.(PubMed)

Key points from the abstract and related work:

• Turbines extract momentum from the wind, slowing near-surface winds over large arrays.
• This changes wind stress at the sea surface and the structure of the upper ocean mixed layer.
• In their simulations, the cumulative reduction in wind stress over big wind clusters leads to:
  • Sea surface warming of ~0.3–0.4°C in the farm regions.
  • A shallower mixed layer – less vertical mixing.
  • Upward heat fluxes from the ocean that destabilize the atmospheric boundary layer and partially offset the turbine wake deficits.(PubMed)

In plainer language:
if you cover a stratified coastal sea with dense offshore wind farms, you don’t just harvest “free” wind – you also rewrite the local heat exchange between ocean and atmosphere.

That is exactly the kind of physical interference climate science normally takes very seriously – except, as your source notes, when it happens to a favoured technology.

Local warming ≠ global catastrophe – but it is climate-relevant

Is 0.3–0.4°C a big deal?

• Globally, we’ve warmed the planet by about 1.2°C since pre-industrial times.
• The Seo result is local, not global, and happens in a specific seasonal/stratified regime.
• Still, in coastal ecosystems, few-tenths-of-a-degree changes in surface temperature and mixed-layer depth absolutely matter for biology and chemistry.

And this study does not stand alone. Other modelling of large North Sea wind clusters has found:

• Up to ±10% changes in annual primary production (phytoplankton growth) downstream of big offshore wind arrays, with knock-on effects for food webs and deoxygenation in bottom waters.(Frontiers)
• Structural changes in stratification, currents and turbulence – enough that offshore wind is now treated as a new anthropogenic forcing in some regional climate and ecosystem models.(Frontiers)

Taken together, this means:

Large-scale offshore wind build-out is not just “put some turbines in the sea and be done”.
It is a deliberate physical modification of shelf-sea climate and ecosystems.

That doesn’t automatically make offshore wind “worse than coal” – but it does make the “harmless and purely green” story scientifically dishonest.

We’ve seen this movie on land already

The idea that wind farms reshape local temperature is not new.

A 2012 satellite study of massive onshore wind farms in West Texas found that:

• Night-time land surface temperature over wind farm areas warmed by about 0.7°C per decade between 2003 and 2011 relative to surrounding areas.(atmos.albany.edu)

The mechanism is very similar: turbine-induced turbulence mixes warmer air aloft with cooler air near the ground at night, raising surface temperature. The authors themselves stressed that the effect was local and small compared with global warming – but they also made it clear that wind farms do change local climate.

So the new offshore study is not some bizarre anomaly. It’s part of a consistent pattern:

Industrial-scale wind power reshapes boundary-layer physics wherever it is deployed.

Plastic dust, noise and wildlife – the rest of the iceberg

The R24 text also lists a series of non-thermal impacts: microplastics from blades, ecosystem disruption, birds and bats, noise, infrasound. Let’s separate what we actually know from social-media horror stories.

Microplastics from turbine blades

Two recent quantitative studies:

• A 2025 study on Dutch North Sea wind farms estimates that a modern 15 MW turbine with leading-edge protection sheds about 240 g of microplastics per year through blade erosion. Total current emissions from all Dutch offshore turbines come out around 100 kg/year.(wes.copernicus.org)
• A separate analysis of Danish wind farms finds 30–540 g of plastic per blade per year, with offshore turbines losing more material than onshore ones; total Danish fleet emissions are about 1.6 tonnes per year, still far below tyre and road-marking microplastics.(MDPI)

Industry-aligned groups like WindEurope lean on those numbers to argue that wind-blade microplastics are on the order of 0.0005% of national microplastic emissions in the Netherlands.(WindEurope)

Bottom line: the emissions are real but small in the current fleet. The risk is not today’s numbers, but the direction of travel: multiply capacity by a factor of five or ten, and this becomes less trivial – especially in semi-closed seas where pollutants accumulate.

Ecosystems, birds, bats and marine mammals

• Offshore wind foundations and wake effects alter hydrodynamics and stratification, which in turn affects plankton, fish and benthic communities; some areas see increased productivity, others reduced, and models show spatial patterns of winners and losers.(Noordzeeloket)
• Construction noise (especially pile-driving) can disturb and injure marine mammals and fish if not mitigated; this is serious enough that environmental agencies mandate seasonal restrictions and noise-abatement technologies.(tethys.pnnl.gov)
• Bird and bat mortality is well-documented for onshore wind; offshore risks are more species- and site-specific but clearly non-zero.(ResearchGate)

Claims that offshore wind is the primary cause of recent whale strandings along the US East Coast remain unsupported by the evidence; NOAA explicitly states that there is no scientific link at this point, even while acknowledging that noise and habitat change are genuine concerns that must be managed.(fisheries.noaa.gov)

Infrasound and human health

The infraääni point is where rhetoric usually outruns data:

• Controlled experiments with 72 hours of simulated wind-turbine infrasound in noise-sensitive volunteers found no measurable adverse health effects compared with sham exposure.(ehp.niehs.nih.gov)
• A broader review of health effects concludes that annoyance and sleep disturbance from audible noise and visual factors are real, while direct physiological harm from infrasound at typical setback distances is not supported by current measurements (levels stay well below WHO thresholds).(ScienceDirect)

So yes, people living close to turbines can be genuinely miserable, but the mechanism looks more like chronic stress and nuisance than some exotic low-frequency “radiation”.

So are offshore wind farms “heat pumps” and a “climate hoax”?

The “heat pump” metaphor captures one important truth:

• Large offshore wind farms redistribute heat between ocean and atmosphere and modify local circulation.
• In Seo’s simulations, the net result under stratified conditions is warmer surface waters and more heat transferred upwards.(PubMed)

But there are two big misconceptions in the “hoax” framing:

1. Wind farms aren’t creating new heat out of nowhere.
   They’re reshuffling existing energy in a system that is already being over-forced by greenhouse gases. The main control knob on global warming is still CO₂, not turbine wakes.
2. The relevant comparison is not “wind vs nothing” – it’s “wind vs fossil”.
   If you remove offshore wind capacity, you don’t get a pristine ocean; you get more coal and gas, with far larger global and regional impacts. The right question is:

Are the additional physical impacts of big wind clusters acceptable, given the avoided fossil-fuel emissions?

From the existing literature, a fair reading is:

• Yes, offshore wind introduces a non-trivial physical footprint on shelf-sea climate and ecosystems.
• No, this does not, in its current form, outweigh the climate damage of burning the fossil fuels it replaces.
• But at the terawatt-scale build-outs now planned for the North Sea and US East Coast, the wake–ocean interactions are big enough that they belong in the same conversation as other climate forcings, not swept under the rug.

The real scandal: risk-blind green marketing

If there is a “hoax” here, it isn’t that offshore wind secretly boils the oceans. It’s the political messaging that insists on presenting a massive industrialization of coastal seas as almost impact-free, and treats anyone who raises physical side-effects as a heretic.

The new Science Advances paper simply forces the issue:

• You cannot fill stratified shelf seas with dense wind clusters and pretend you’re not modifying the regional climate system.
• You cannot talk endlessly about “climate tipping points” and then shrug off modelled 0.3–0.4°C local warming and ecosystem shifts because they come from your favourite technology.

A grown-up energy policy would do three things at once:

1. Admit that offshore wind is a strong, but not clean, intervention – a physical engineering of coastal climate.
2. Integrate these effects into official climate and marine-planning models, instead of limiting analysis to turbine yield and headline CO₂ savings.
3. Design build-outs and exclusion zones that minimize the most harmful side-effects (stratification hot spots, critical habitats, migration routes) instead of maximising only megawatt-hours.

That’s not as emotionally satisfying as shouting “CO₂-cult!” – but it’s far closer to what the current science actually supports.

📚 Sources

• Hyodae Seo et al. (2025), Sea surface warming and ocean-to-atmosphere feedback driven by large-scale offshore wind farms under seasonally stratified conditions, Science Advances 11(45): eadw7603.(PubMed)
• Ute Daewel et al. (2022), Offshore wind farms are projected to impact primary production and bottom water deoxygenation in the North Sea, Communications Earth & Environment 3, 292, and Hereon summary.(ResearchGate)
• Marco Caboni et al. (2025), Estimating microplastic emissions from offshore wind turbine blades in the Dutch North Sea, Wind Energy Science 10, 1123–1136.(wes.copernicus.org)
• Leon Mishnaevsky Jr. et al. (2024), Microplastics Emission from Eroding Wind Turbine Blades: Preliminary Estimations of Volume, Energies 17(24): 6260.(MDPI)
• Liming Zhou et al. (2012), Impacts of wind farms on land surface temperature, Nature Climate Change; Guardian coverage “Windfarms can increase night time temperatures, research reveals”.(atmos.albany.edu)
• European Environment Agency (2024), Harnessing offshore wind while preserving the seas.(Euroopan Ympäristökeskuus)
• NOAA Fisheries, Offshore Wind Energy: Assessing Impacts to Marine Life.(fisheries.noaa.gov)
• WindEurope, Dis and misinformation: nature and health.(WindEurope)
• New York Post